Bell actuating mechanism



Feb. 6, 1951 w. e. HOLMES 'BELL ACTUATING MECHANISM Filed May 8, 1948 4i ,1 a; 2 z Z? 6 3} .J 3 wi5 Patentecl Feb. 6 1 951 zsitsn UNITED STATES PATENT OFFICE 1 Willis G. Holmes, Pembroke, Mass.

Application May 8, 1948, Serial No. 25,935

8 Claims. (Cl. 177-7) To obtain the maximum of sonic energy from an alarm bell, it is desirable to have the striker contact the gong at the end of a long stroke and substantially simultaneously to interrupt the electrical circuit of the driving electromagnets so that the striker will not be retained in contact with the gong after completion of its stroke. The length of the stroke is largely determined by the bell design; whereas adjustments are usually provided permitting compensation of each individual bell for dimensional variations in the component parts.

Objects of this invention are to provide an alarm bell which has an exceptionally long striker movement, which has a striker readily adjustable to contact the gong at the end of its stroke, which has electrical contacts adjustable to open at the most advantageous point in the striker movement, in which such adjustments can be made after the bell has been assembled and without removing the actuating mechanism from its housing, which is simple and rugged in construction, and which advances the art of bell manufacture generally.

In one aspect the invention contemplates an alarm bell actuating mechanism having a supporting frame to which two guide pieces are affixed. A plunger assembly slidably supported by the frame includes a striker with an armature fastened thereto so that the assembly moves parallel to its longitudinal axis upon the energization of an electromagnet. To obtain a large axial movement of the striker, a restraining member is fixed at its center to the plunger assembly and with its ends sliding on the respective guide pieces.

In another aspect a normally closed switching element is located upon the frame and electrically connected in series with the electromagnet. The plunger assembly has a switch operating member mounted coaxially adjustable on one end of the plunger and a striker mounted coaxially adjustable on the other end of the plunger whereby the time of opening of the switching element and the effective stroke of the striker can be independently varied.

In a specific aspect the bell actuating mechanism comprises a pair of cylindrical guide pieces, two electromagnets and a normally closed switching element affixed to a supporting frame. This frame also slidably supports a plunger assembly between the electromagnets which moves parallel to its longitudinal axis upon the energization of the electromagnets.

I The plunger assembly includes an internally threaded plunger with a shoulder on one end thereof, an armature member, and a restraining member fastened at their respective centers to the shoulder end'of the plunger by a nut. The restraining member has an aperture on each end iereof for engaging the respective guide pieces I aflixed to the supporting frame so that the striker has a long axial movement. Adjustment of the time of opening at the switching element is ob tained by varying the engagement of a switch operating member with the internal threads of the shouldered end of the plunger. The movement of the striker is adjusted in analogous manner by the threading thereof into the opposite end of the plunger.

These and other objects and aspects of the invention will be apparent from the following detailed explanation illustrating the invention with reference to a concrete embodiment thereof. The description refers to the drawings in which:

Fig. 1 is a side elevation view of the actuating mechanism with one side of its housing removed;

Fig. 2 is a cross sectional view on line 22 of Fig. 1;

Fig. 3 is a fragmentary cross sectional view on line 3-3 of Fig. 1; and

Fig. 4 is a fragmentary cross sectional view on line 22 of Fig. 1.

As is thus illustrated in Fig. 1 the bell actuating mechanism comprises a supporting frame 6 of brass or other non-magnetic material carrying a plunger assembly i, an electromagnet assembly 8, and a switching element 9.

The frame 6 includes a bracket ll fastened to a bell housing 12 by the screws 13. Two threaded holes [4 are provided'in the bracket i i to engage the screws Hi (Fig. 2) for securing a cover ll to the housing l2. A U-shaped frame member i8 is also fastened to the bracket 1 I by the screws 59, two of which pass through clearance holes in each of the respective sides of the bracket ii to thread into holes tapped in the adjoining legs 2! of the Ll-shaped bracket [8. v

The end of each leg 2! is bent inwardly to form a lip '22 upon the top of which is carried a cylindrical guide piece 23 of brass or other material preferably nonmagnetic. The end of each piece '23 adjacent the lip 22 is reduced in diameter as at 26 so that it engages an aperture 2? (Fig. 3) in a leaf spring which acts as a restraining member 28 whose function will be described in detail hereinafter. The opposite end of each guide piece 23 supports a plastic cross member 29 upon which is mounted the switching element 9. The guide pieces 23 and the cross member 29 are fastened in position by screws 3 i, each of which projects through a hole near one of the respective ends of the cross member 29 and the axial hole in the corresponding guide piece 23 to engage the threads of a hole tapped in the adjacent lip 22.

The switching element $3 includes a stationary contact 32 riveted to one end of an arm 33. The other end of the arm 33 is secured to the crossv member 29 by two cap screws and their engaging nuts 35. The movable contact 37 is riveted to the free end of a cantilever leaf spring 38 constructed of phosphor bronze or other elastic material which readily conducts an electrical current but which is preferably nonmagnetic. The

opposite end of the spring 38 is joined touthe.

cross member 29 by means of two cap screws ,39 and the mating nuts ll.

The bottom connecting member 42 between the frame legs also acts as a support for two electromagnets 93a and 2317 and their associated magnetic circuit. This magnetic circuit includes the pole-pieces i l-a and 45b of the electromagnets 43a and itb respectively, and a strap of low reluctance material juxtaposed with the connecting member so that the bottoms of therespective pole pieces 1 3a and 46b are magnetically linked. The top of the magnetic circuit is completed by an armature member il which is part of the plunger assembly '1 to be described in detail below. To prevent chattering when the electromagnets 43a and :32) are energized by an alternating current, the pole piece Ma is shaded in the conventional manner by. a short circuitedwinding such as the splitcopper disk 450. which has a diametrical piece resting. in a slot in the end of the pole piece. The pole piece 441). is similarly shaded by the disk 451)., The screws. 23 project upwardly through the connectingmember 12 and the strap ".6 to engage a threaded hole in the bottom of the respective pole pieces. and fi th thereby securing the electromagnets ita and @321 to the supporting frame 18.

The electromagnets and 43b and the normally closed contacts 32 and 37 are. series connected by interconnecting the leads tea and 4919 which are taken off at the bottom ofthe respective magnet windings. A fiber washer 5| is inserted between the strap tie and the respective electromagnets and 53h so that the leads are protected from abrasion. The second lead 52a. from the electromagnet 43a is fastened under one of the nuts 3! securing the cantilever spring 38 to the cross member 29. The stationary contact arm 33 is similarly connected to one endlof a lead 56, the other end of which is joined to a conductor 53a of an energizing source of either alternating or direct current (not shown), for example, by the solderless connector 54. The

lead 522) is directly coupled to the other source conductor 53b in an analogous manner. To prevent any strain on the mechanism the leads 59 and 53b pass through an insulating block 55 fastened to the cover H.

The plunger assembly l is slidably mounted in holes located in the cross member 29 and the frame connecting member 22 so that the assembly is positioned between the electromagnets 43. The assembly 7 comprises a hollow plunger 56 with. an internal thread and a striker 51 with one end threaded into the lower end of the plunger. The other end of the striker 52' projects through an aperture 58 (Fig. 2) in the casing I2 to contact the inner surface of a gong 59 upon the 4 energization of the electromagnets 33. The effective length of the striker 51 is adjusted by varying the number of threads engaged in the internal threads of the plunger 56. The adjusted position is maintained by a lock washer 6| and a check nut 62 (Fig. 4). A coil spring 63 is located between the strap 45 and the nut 62 to furnish a restoring movement to the plunger assembly I.

A shoulder is provided upon the upper end of the plunger 56 to carry the armature member 4?, the leaf spring restraining member 28 and a thin separating Washer es. These members are maintained in position by a lock washer 54 and a check nut 56 which engages external threads 65-uponthesurface of the plunger 55 having reduced cross sectional area. A thin leaf 6! of bronze or other nonmagnetic material is inserted between the armature member 4! and the plunger shoulder.

Theswitchcperating member comprises afiben washer fill-supported bya fiber sleeve. H which. passes through acIearancehole in theleafspring 38;: The. sleeve H and thewasher fielarersecured,

to. the. plunger 56. by means, of j a round headed cap screwl2 and a checknutlS. As the plunger assemblyldescends, the, washer 59 contacts the switch leaf spring 38-and deflectsit downwardly,

so that the contacts. 32 and 3] open thereby to interruptthe power supply to theelectroma l ets 43. Adjustments of the time of opening of the contacts is madeby varying the engagement of the. screw-:72 andshimming the sleeve Has:

required.

In the deenergizedposition shown inyFig. 1, thespring 63.;forces the plunger assembly Lupe Wardly so that the washer 69 is not in contact.

withutheleaf spring 38,: and-thecontacts Hand 31? are therefore inthe closedposition. When- 5T contacts.thegongje, theleaf spring restrain,

ing member zt sliding along the guide pieces 23; Thestriker 5? is adjusted, asdescribed in detail heretofore, so that the restraining member 23-- comes in contactwith thetop oftheframe lips Z'Zjustbefore the, striker 5? contacts the gong 59, the follow throughbeing provided by the The elasticity. of the. restraining member; 28. opening of the contacts 32 and 3? is regulated to take place substantially at the time the striker E'icontactsthe gong 59.

Itisapparent from the above that both of these adjustments can ,ber readily made after-the actuating mechanism hasbeenmounted in the casing IZthereby permittingthe optimum. settings for.

each bell to'be obtained by actual tests. Another. distinct advantage is thepossi-bility of using. the

same mechanism and casing forseveral sizes of bells, only the striker E'Land the gong 59 being changed in eachcase.

It should .be. understoodthat the present dis.-

closure is for the purpose of illustration only and.

that this invention includes all, modifications and equivalents,.whi ch fall within the scope .of the,

appended claims.

I claim:

1. An electrical actuating mechanism for a.

This moves the attachedthe lengths of the guide pieces, thereby to provide large axial movement of said striker.

2. An electrical actuating mechanism for a bell comprising a supporting frame, apair of parallel cylindrical guide pieces affixed thereto, two electromagnets fastened to said frame, and a plunger assembly slidably supported between said electromagnets by said frame including a striker, an armature fastened to said striker and movable parallel to the longitudinal axis thereof upon the energization of said electromagnets, and a yieldable restraining member fixed at the center to said plunger assembly and having an aperture in each end thereof for engaging the respective guide pieces, the travel of the ends of the restraining member between limits in opposite directions being determined by the lengths of the guide pieces, thereby to provide large axial movement of said striker.

3. An electrical actuating mechanism for a bell comprising a supporting frame having two guide pieces affixed thereto, an electromagnet fastened to said frame, and a movable assembly including a plunger slidably supported by said frame, an armature member movable parallel to the longitudinal axis of said plunger assembly, a yieldable restraining member having ends sliding on the respective guide piC6S,'th6 center of both of said members being fastened to one end of said plunger, the travel of the ends of the restraining member between limits in opposite directions being determined by the lengths of the guide pieces, and a striker mounted for axial adjustment on the other end of said plunger whereby the stroke of said striker can be readily varied.

i. An electrical actuating mechanism for a bell comprising a supporting frame; a pair of cylindrical guide pieces aflixed thereto, two electromagnets fastened to said frame, and a movable assembly slidably supported between said electromagnets by said frame and including an internally threaded plunger with a shoulder upon one end thereof having external threads, a nut engaging the external threads, an armature fastened upon said shoulder by said nut and movable parallel to the longitudinal axis of said assembly, a yieldable restraining member having an aperture in each end thereof for engaging the respective guide pieces, the center of said member also being fastened upon said plunger shoulder by said nut, the travel of the ends of the restraining member between limits in opposite directions being determined by the lengths of the guide pieces, and a striker threaded into the other end of said plunger whereby the stroke of said striker can be readily varied.

5. An electrical actuating mechanism for a bell comprising a supporting frame having two guide pieces affixed thereto, an electromagnet fastened to said frame, a normally closedswitching element located upon said frame and electrically connected in series with said electromagnet, and a plunger assembly slidably supported by said frame and including a striker, an armature member movable parallel to the longitudinal axis of said assembly, a yieldable restraining member having itsends sliding on the respective guide pieces, the center of both of said members being fastened to one end of said plunger assembly, the travel of the ends of the restraining member between limits in opposite directions being determined by the lengths of the guide pieces, and a switch operating member mounted for axial adjustment on said assembly whereby the time of opening of said switching element can be readily varied.

6. An electrical actuating mechanism for a bell comprising a supporting frame, a pair of parallel cylindrical guide pieces affixed thereto, two electromagnets fastened to said frame, a normally closed switching element located upon said frame and electrically connected in series with said electromagnets, and a plunger assembly slidably supported between said electromagnets by said frame and including an internally threaded plunger with a shoulder upon one end thereof having external threads, a nut engaging the external threads, an armature member fastened upon said shoulder by said nut and movable parallel-to the longitudinal axis of said assembly by the energization of said electromagnets, a yieldable restraining member having an aperture in each end thereof for engaging the respective guide pieces, thecenter of both of said members being fastened to the plunger shoulder by said nut, the travel of the ends of the restraining member between limits in opposite directions being determined by the lengths of the guide pieces, a switch operating member threaded into the shouldered end of said plunger, and a striker engaging the plunger whereby the time of opening of said switching element can be readily varied.

7. An electrical actuating mechanism for a bell comprising a supporting frame having two guide pieces aifixed thereto, an electromagnet fastened to said frame, a normally closed switching element located upon said frame and electrically connected in series with said electromagnet, and a plunger assembly slidably supported by said frame and including a plunger, an armature member movable parallel to the longitudinal axis of said assembly by the energization of said electromagnet, a yieldable restraining member having its ends sliding on the respective guide pieces, the centers of both of said members being fastened to one end of said plunger, the travel of the ends of the restraining member between limits in opposite directions being determined by the lengths of the guide pieces, an adjustable switch operating member mounted for axial adjustment on said end of said plunger and an adjustable striker mounted for axial adjustment on the other end of said plunger whereby the time of opening of said switching element and the effective stroke of said striker can be independently varied.

8. An electrical actuating mechanism for a bell comprising a supporting frame having a pair of parallel cylindrical guide pieces affixed thereto,

two electromagnets fastened to said frame, a

normally closed switching element located upon said frame and electrically connected in series with said electromagnets, and a plunger assembly slidably supported between said electromagnets by said frame and including an internally threaded plunger with a shoulder upon one end thereof, a nut, an armature member movable parallel to the longitudinal axis of said assembly by the energization of said electromagnets, a

amnmn;

7 8 yieldable restraining member: having: an apex-e I w tu-rein each end thereoffor engagementwwithethe REFERENCES CITED respective guid pieces, the center of: both. of 3 The-1911mm; ferences/erect record in'the said members; being fastened to .the shouldered: l e iv isli ent; end-:of-said plunger by said nut the-travel 'of the; 5: UNITEDLSTATES'PATENTS;

ends of" thearestrainingmember between limits.

inopposite; directions being: determinedibyvthe Number I Date lengthsof the guide pieces, a, switch operating 1,915,035; m 1-912 memberthreaded intothe shouldered end-of said stutter 1913 plunger; and astriker threadedinto .the opposite 10 5 5 M g F 1917 end of said plunger whereby the time.- of open-1 Elsh- 0915- ingof 'saidswitehing element. and. the eflective stroke of said strikercan'be independently .variedz.

WILLIS G1. HOLMES; 

